Rolling mill



M y 1954 F. P. DAHLSTROM 2,677,978

ROLLING MILL Filed March 22, 1950 4 Sheets-Sheet l INVENTOR. Ike 20m. ma BY I I I ATTORNEY May 11, 1954 F. P. DAHLSTROM ROLLING MILL 4 Sheets-Sheet 2 Filed March 22, 1950 INVENTORY FAME/Q04 HLJ B a y 11, 1954 F. P. DAHLSTROM 2,677,978

ROLLING MILL Filed March 22, 1950 4 Sheets-Sheet 3 IN VEN TOR.

Fee/w 1? DA Hum 4 ATTORNEY May 11, 1954 v F. P. DAHLSTROM 2,677,973

ROLLING MILL Filed March 22, 1950 4 Sheets-Sheet 4 IN VEN TOR. F199 VK PDQ/{1.5720114 ATTORNEY *4 44 l l T Patented May 11, 1954 9 Claims.

This invention relates in general to metal rolling and more particularly the cold rolling, to accurate and substantially uniform cross section, of relatively thin strip or sheet metal. The invention provides a mill which enables the strip material undergoing reduction to be uniformly elongated across the full width thereof. This result is achieved by a mill construction which permits corrective adjustments to be made, during operation of the mill, of the rolling pressures effective on the strip at a plurality of localized areas crosswise of its width, thereby to correct all irregularities arising from overrolling or underrolling of any portion of the strip, and to main tain at all times a complete control of the pass contour of the mill.

As will hereinafter appear my invention makes it possible to obtain skin pass or temper rolling of thin metal strip without resort to the excessively high rolling pressures and tensions heretofore employed, and by the use of a small-sized inexpensive mill whose power requirements and operating costs are extremely low.

With the above and other objects in View, as will hereinafter appear, the invention comprises the devices, combinations, arrangements of parts and methods of rolling hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and th advantages attained thereby will be readily understood by those skilled in the art.

the accompanying drawings,

Fig. i is a vertical sectional view on line l-i of Fig. 2, of a rolling mill in accordance with my invention.

2 is a right-hand side view of said mill, with certain parts omitted.

3 is a top plan view, partly in section, the section being taken on the line 3-4-3 of Fig. 1.

Fig. i is a horizontal sectional view substantially on the line kl of Fig. 1.

Like reference characters refer to like parts in the different figures.

In the illustrated embodiment of my invention the reducing pass of the mill is provided between upper and lower working rolls I and la respectively, which are of relatively small diameter. The illustrated mill provides upper and lower backing rolls, desi nated 2 and 2a respectively, to which the power for driving the mill is applied, as indicated by the broken line showing in Fig. 2 of suitable coupling devices associated with the necks of said backing rolls. The latter are of considerably larger size than the Work rolls, the

diameters of said backing rolls being enough in any case to sustain the rolling load, and to transmit to the work rolls, as hereinafter described, the required rolling pressures.

The several rolls, as thus far described, are supported in a suitable housing, here shown as consisting of a pair of uprights 3-3, each of which has a vertical window t for the containment of suitable bearing blocks or chocks for the neck portions of said rolls. For that purpose, as best shown in Fig. 1, each housing window contains at its lower end a suitable chock 5, said two chocks 5 receiving the necks 5, 6 of the lower backing roll 20:, and each chock 5 above this neck bearing being formed with a window I which contains a pair of suitable small opposed chocks 3-8 for the respective necks 9-9 of the two small diameter working rolls l and la. Each housing window t contains at its upper end a suitable chock W, said two checks ll-H! receiving the necks i l-li of the upper backing roll 2. These upper checks lE-iil are contacted by conventional screw-downs l2l2, which are threaded in the housing uprights S S, and are adjustable in the usual manner to regulate the thickness of the pass and the amount of rolling pressure exerted therein on the strip.

According to my invention the required rolling pressures are transmitted to the work rolls through a rolling element of elastic character, which is interposed between at least one of the small work rolls and its associated backing-up roll. In the illustrated mill, one such flexible rolling element is shown in the form of a hollow or tubular roll it, which is of a diameter greater than that of the work rolls but less than that of the backing-up rolls; it is to be understood that the diameter, as well as the wall thickness of the hollow roll it, are selected with due regard to the strength required to resist the roll-separating forces effective on the work rolls and to transmit the required rolling pressures and also with due regard to the degree of flexibility desired for this element, in the operation of the mill.

Said hollow roll it is here shown as interposed between the upper work roll 5 and its associated backing roll 2, in position to drive the former from the latter, and to transmit the required rolling pressures. Hollow roll it is prevented from shifting endwise by rollers 3?, 3?, Figs. 2 and i, which bear against its ends, said rollers being supported by suitable brackets 35, it attached to the housing uprights 33. Hollow roll it is maintained laterally in the pressure-transmitting position of Fig. l by a plurality of pairs of narrow rollers, arranged to bear against its periphery on opposite sides (see Fig. 4). In the illustrated embodiment of my invention nine such pairs of narrow rollers are shown, namely three centrally arranged pairs i i-Hid, i5-l5a and i5l6a, two end pairs l'!l1a and lB-lBa in the zones of the opposite margins of the strip, and two groups of intermediate pairs i 91-43% 2ll20a and 2l2la, 22-22a, distributed across the strips intermediate zones, between its central portion and its marginal portions.

Each such narrow roller of every pair is suitably journalled on a horizontal pivot pin 23, carried by a yoke 2 which provides an outwardly projecting rod 25. All such individual yokes for the row of rollers 14-22 inclusive on one side are slidably mounted in a crossbar 26 of the housing, and all such yokes for the opposite row of rollers Met-22a inclusive are slidably mounted in an opposite housing crossbar 26a. Each individual projecting rod 25 is contacted by its own operat ing lever, the several levers designated by numerals 2'! for the rollers M to 22 inclusive being pivoted on a cross shaft 28 of the housing, and the several levers designated by numerals 21a for the rollers its to 22a inclusive being pivoted on cross shaft 28a of the housing.

Above the pivotal shafts 28 and 280;, the housing provides crossbars 29 and 29a respectively, the former to limit clockwise rocking of the several levers 27, and the latter to limit counterclockwise rocking of the several levers 27a. These crossbars serve as positive stops to limit the outward movements of the two rows of rollers I l-22 inclusive and Uta-22a inclusive. With the strip traveling through the mill in the direction of arrow A, Fig. l, the several rolls are rotating, as shown by their respective arrows, in directions that tend to force the hollow roll [3 to the right.

In this situation, the crossbar 29a is arranged to be contacted by all of the levers 21a, thereby to keep the axis of hollow roll I3 in substantial parallelism with the axes of the other rolls of the mill. Under those conditions, there is left as shown a slight clearance between the several levers 2? and the stop surface of the crossbar 29, which allows the hollow roll !3 to operate in a slightly flexed or flattened condition, under the rolling pressures which it transmits. Such clearance is taken up whenever the two levers of any pair of opposed narrow rollers are actuated to move said rollers toward each other, such move ments being in opposition to the aforesaid flattening of the hollow roll l3, and creating forces which tend to flatten same in a direction substantially at right angles to the first mentioned flattening. In other words, the hollow roll i3 is deformable sectionally by extraneous forces producing inward movement of any pair or pairs of the opposed narrow rollers in such manner as to increase the effective rolling diameter of said hollow roll in the region or zone thereof contacted by the so-moved narrow rollers.

For obtaining such inward movements of each pair of narrow rollers, the two levers 21 and 21a of each pair of opposed rollers are connected at their upper ends in the manner best shown by Figs. 1 and 3. That is to say, one lever of every such pair has pivoted to it at 30, a bracket 3i, which carries a single-acting hydraulic cylinder; these several cylinders, to denote the association of each with only a single pair of opposed narrow rollers (l t-Ma, l5i5a, etc.) are designated by corresponding numerals carrying the letter b,-

there being in the arrangement shown three cylinders I 41;, 15b and I6!) for the three central pairs-- of opposed rollers, two cylinders lb and 812 for the two end pairs of opposed rollers, and the other cylinders lab, 2% and 2), 22b, for the intermediate pairs of opposed rollers, which are distributed across the strips intermediate zones, between its central portion and its two marginal zones.

Within each cylinder is a suitable piston 32, having secured thereto a rod 33 which extends across the upper backing-up roll 2, for pivotal connection at 34 to the other lever (27 or 27a) of the pair of levers which actuate the two rollers of that-particular cylinder. Communicating with each cylinder is a suitable conduit 35 for conducting fiuid under pressure thereto and therefrom, there being provided for each conduit a suitable valve device, not shown, for manipulation by the mill attendant or operator, to secure admission of such fluid, at any desired pressure, to any selected cylinder or cylinders, and the exhaust of such fluid therefrom. In this way any selected pair or pairs of opposed narrow rollers can be forced inwardly, to exert in their 'espective regions, localized compressive forces of variable intensity on the hollow roll 53, substantially at right angles to the compressive forces produced thereon by the required rolling pressures which it transmits to the work rolls of the mill. The result in each region or zone of application of such extraneous forces is to increase the hollow rolls effective rolling diameter and hence its pressure against the work roll i in said zone or region, but without materially affecting the hollow rolls working diameter or its transmitting pressure in other zones or regions across the width of the strip.

It will be evident that the above-described strip mill gives complete and positive contour control, by enabling the operator during the operation of the mill to increase or decrease, as required, the effective rolling pressure in localized areas crosswise of the strip whenever it appears that the strip is being underrolled or overrolled in any such area. Such contour control is particularly useful in skin pass or temper rolling where, because of the crown and relative softness of the strip, the latter is peculiarly susceptible to highly irregular and nonuniform elongation crosswise of its width, giving rise to buckles, rlfiies and other undulatory deviations from flatness in the finished product. Heretofore, it has been the general practice to counteract all such tendencies by temper rolling the thin strip in large heavy duty rolling mills, operating under abnormally high rolling pressures, many times in excess of the ef fective yield point of the material undergoing reduction therein. As pointed out in McConnell Patent No. 2,271,459, dated January 27, 1942, it is not uncommon, in these heavy duty mills, to use rolling pressures as high as 100,000 pounds or more per linear inch of strip width. My invention enables highly satisfactory temper rolling of thin metal strip to be performed by a moderate size mill, working under relatively low rolling pressures and having relatively low power requirements. This is because my mill affords at all times during operation an effective localized control and adjustment of the working pressures, for the elimination, as soon as they appear, of buckles, riffies or other evidences of nonuniform elongation in the finished product.

That is to say, either in temper rolling or in other cold rolling by my mill, the emerging product may for various reasons show signs (as buckles) of being overrollcd in its central regions, either from having had too much crown, or from undue heating-up and expansion of the backing rolls, or from any other cause. In that event, the mill attendant or operator is enabled by my invention to take effective corrective measures to insure the delivery of a completely fiat product, free of buckles, riiiies or other irregularities. This correction is accomplished, in the case of central Zone overrolling, either by relieving such pressures as may prevail in cylinders Mb, i522 and Nib, or by admitting fluid under appropriately graduated degrees of pressure, to those cylinders, such as ill) to 22?; inclusive Whose pairs of opposed rollers contact the hollow roll IS in zones or regions beyond and outside of the central region that overlies the over-rolled central zone of the strip. The several of opposed narrow rollers actuated by these cylinders exert pressures on roll it that tend, in the regions of their contacts therewith, to reduce the out-of-roundness of said roll, thereby to increase the pressures transmitted in such regions to the work roll 5, so as to bring the rate of elongation in these regions up to that prevailing in the central region of the strip.

Similarly, whenever the emerging strip shows signs (as riflles) of being over-rolled along its marginal zones, the mill operator can either relieve such pressures as may prevail in cylinders ill) and E8?) or else admit fluid under appropriately graduated degrees of pressure to the cylinders E411, E511, lfib, 20b and 2H). This last will apply extraneous forces through their associated narrow rollers to deform the hollow roll is locally in their respective regions, thereby to increase the pressures on the work roll l in those regions, and to bring the strips elongation in such regions up to that prevailing at the marginal portions of the strip. It will thus be evident that my invention provides at all times a complete and very sensitive control over the pass contour of the m ll, which is extremely useful, not only for temper or skin pass rolling, but also for other cold rolling operations involving more sizeable reductions in the thickness of the stock.

I claim:

1. In a multi-high rolling mill, a pair of small diameter work rolls providing a pass for the material undergoing reduction, a large diameter backing-up roll associated with each work roll, a hollow roll of sufficient flexibility to be slightly flattened by the rolling pressures employed for such reduction, interposed in pressure-transmitting position between at least one of said work rolls and its associated backing-up roll, and means operable on said hollow roll during opera tion of said mill, to produce flattening thereof in a direction substantially at right angles to said first mentioned flattening.

2. In a multi -high rolling mill, a pair of small diameter worl: rolls providing a pass for the ma- -erial undergoing reduction, a large diameter backingup roll associated with each work roll, a hollow roll element, slightly deformable sectionally under the rolling pressures employed for such reduction, interposed in pressure-transmitting position between at least one of said work rolls and its associated backing-up roll, and means for applying to said element during operation of said mill, extraneous deforming forces in opposition to the deformation produced by said rolling pressures.

3. In a multi-high rolling mill, a pair of small diameter Work rolls providing a pass for the material undergoing reduction, a large diameter backingup roll associated with each work roll, a hollow roll element, slightly deformable sectionally under the rolling pressures employed for such reduction, interposed in pressure-transmitting position hetween at least one of work rolls and its associated backing-up roll, and means selectively operable to vary, in localized regions along its length, the amount of such deformation, therehy to change, in such region or regions, the rolling pressure transmitted by said element to said work rolls.

r. in a multi-high rolling mill, a pair of small diameter work rolls providing a pass for the material undergoing reduction, a large diameter backingmp roll associated with each work roll, a hollow roll element slightly deformable sectionally under the rolling pressures employed for such reduction, interposed in pressure-transmitting position between at least one of said work rolls and its associated backing-up roll, and means selectively operable to exert extraneous deforming forces on said element, in localized regions along length, thereby to increase in such region or regions, the rolling pressures transmitted by such element to said work rolls.

5. A mill for rolling metal strip comprising a pair of work rolls between which the strip is passed, said work rolls being of small enough diameter to effect said strips reduction under moderate or relatively light rolling pressures, a backing-up roll of relatively large diameter in load-sustaining relation to each work roll, a hollow sectionally deformable roll maintained between one or said work rolls and its associate-:1 backing up roll across the full width of the strip, and means selectively operable on said hollow roll, at a plurality of regions along its length, to impose localized extraneous deforming pressures thereon in a direction to increase its working diameter in said selected region or regions, thereby to increase the effective rolling pressure in said region or regions, on the strip undergoing reduction.

6. In a multi-high rolling mill, 2. pair of small diameter work rolls providing a pass for the material undergoing reduction, a large diameter backing-up roll associated with each work roll, cylindrical pressuretransmitting means interposed between and in rolling contact with a work roll and its associated backing-up roll, said means being tubular and of suiilcient flexibility to flatten slightly under the rolling pressures employed for such reduction, and a plurality of pairs of opposed elements arranged along the sides of said hollow cylindrical means in position to resist, in selectively variable degrees, said flattening action, thereby to increase or decrease, in the region or zone of any such pair, the rolling pressures ransmitteol by said hollow cylindrical means.

'2. In a multi-high rolling mill, a pair of small diameter work rolls providing a pass for the material undergoing reduction, a large diameter backing-up roll associated with each work roll, cylindrical pressure-transmitting means interposed between and in rolling contact with a work roll and its associated backing-up roll, said means being hollow and of sufiicient flexibility to flatten slightly under the rolling pressures employed for such reduction, a plurality of pairs of opposed relatively narrow rollers adapted to against the sides of said hollow cylindrical means, a centrally pivoted lever hearing at one end against each narrow roller, to maintain same in contact with said hollow cylindrical means, and means operative on the other ends of the two levers of each pair of said narrow rollers to move the latter inwardly in unison, in opposition to the flattening action of said cylindrical hollow means.

8. A mill for rolling metal strip comprising a pair of work rolls of small enough diameter to effect said strips reduction under moderate or relatively-light rolling pressures, a relatively large diameter backing-up roll in load-sustaining relation to each work roll, cylindrical pressuretransmitting'means interposed between and in rolling contact with a Work roll and its associated backing-up roll, said means being hollow and of sufficient flexibility to flatten slightly under the rolling pressures employed for such reduction, and means selectively operable on said hollow cylindrical means, at a plurality of regions across the width of the strip, to vary the extent or de gree of its flattening, thereby to increase or decrease, the case may be, the eifective rolling pressure in each region on the strip undergoing reduction.

9. In a mill for rolling metal strip, the combination with a pair of work rolls providing a reducing pass for the strip material, of means for resisting, during operation of said mill, the separating forces effective on said work rolls, said means including a sectionally deformable tubular member maintained in rolling contact with one of said work rolls, and means selectively operable at each of a plurality of regions across the Width of said strip for exerting localized extraneou deforming forces on said tubular member, in a direction to increase its eifective diameter, thereby to increase in such selected region or regions the rolling pressure on said strip material.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,870,509 Heiden Aug. 9, 1932 1,964,893 Rohn July 3, 1934 2,187,250 Sendzimir W Jan. 16, 1940 

